The present invention relates to the field of wireless communications devices, and more particularly to a rotary damper for use in wireless communications devices.
Wireless communications devices, such as cellular telephones, typically have a portion of their housings that rotate about one or more hinge points to selectively cover and uncover the keypad, display, etc. A common example of such a moveable cover is known in the art as a flip cover. It is desirable for these flip covers to have some amount of resistance when being opened and/or closed so that the user does not perceive the device to be of poor or flimsy construction.
One typical method providing such resistance is to employ a frictional fit between the flip cover and the main housing. However, this approach relies on tight tolerances and is also subject to wear over time. Another approach is to employ a rotational damper, or dashpot, to resist the rotational movement of the flip. This approach is useful, but consumes valuable space.
Wireless communications devices typically announce an incoming call, or other alarms, by ringing. However, audible ringing is not appropriate in some situations, so many cellular telephones are equipped with alternative announcement means such as a vibrator for generating a vibratory motion to alert the user. Such vibrators typically operate by moving a weight non-symmetrically within the main housing or flip cover so as to shift the center of gravity of the device.
Due to the emphasis on decreased size, space considerations are very important when designing a wireless communications device. As a result, and due to manufacturing considerations, it is preferred that multiple functions be designed into each component. To date however, the space consuming vibrator and the space consuming rotary damper have not been combined. As such, there remains a need for a new design of rotary damper that can be easily manufactured and installed, and that will consume minimal space. Preferably, but not necessarily, such a rotary damper would also include a built-in vibrator mechanism.
Wireless communications devices according to the present invention utilize a rotary damper having motor to selectively dynamically brake the rotational movement between a housing and a cover of a wireless communications device. The motor is secured to either the housing or the cover of the wireless communications device. For purposes of illustration only, the motor will be attached to the housing of a cellular telephone and the cover will be a flip cover. A clutch that is moveable between an engaged position and a disengaged position selectively connects the motor to the flip cover so that the relative rotational movement between the housing and the cover in at least one rotational direction, and preferably both, is resisted by the motor when the clutch is in an engaged position. The clutch preferably includes a coupler axially moveable between a deployed position directly engaging the flip cover and a retracted position disengaged from the cover, and an actuator moveable between a first position and a second position so as to cause the coupler to assume the deployed position and the retracted position, respectively. The coupler may include a plurality of outwardly extending teeth that mate with corresponding teeth on the cover when the coupler is in the deployed position. The actuator preferably includes a spring to bias the coupler towards the deployed position. A shaft preferably extends through the motor and connects the actuator to the coupler. The coupler may rotate at a slower speed relative to the shaft or may rotate at the same speed.
In some preferred embodiments, the rotary damper includes an eccentric weight rotatably driven by the motor so as to generate a vibration when the clutch is in the disengaged position. This eccentric weight may be attached to the shaft so as to spin therewith. For instance, the motor may, when the clutch is in the disengaged position, intermittently spin the shaft causing the eccentric weight to spin, thereby imparting a shaking motion to the overall phone.
A wireless communications device equipped with the rotary damper of the present invention relies on electromotive damping force from a motor to provide the dynamic braking of the rotational movement between the housing and the cover. Because this electromotive force may be easily controlled, the rotary damper provides greater flexibility in function, such as by allowing the cover to be driven or held open when appropriate. In addition, the incorporation of the optional eccentric weight allows for the rotary damper and the vibrator of a wireless communications device to be combined into a single compact package. The motor of the rotary damper is used to both resist the rotation of the flip cover (via the coupler and shaft) when the coupler is in the deployed position and to spin the eccentric weight, when appropriate, when the coupler is in the retracted position.